v3.8.0.1
Document and Entity Information
12 Months Ended
Dec. 31, 2017
shares
Document - Document and Entity Information [Abstract]  
Document Type 20-F
Amendment Flag false
Document Period End Date Dec. 31, 2017
Document Fiscal Year Focus 2017
Document Fiscal Period Focus FY
Trading Symbol IMOS
Entity Registrant Name ChipMOS TECHNOLOGIES INC.
Entity Central Index Key 0001123134
Current Fiscal Year End Date --12-31
Entity Well-known Seasoned Issuer No
Entity Current Reporting Status Yes
Entity Filer Category Accelerated Filer
Entity Common Stock, Shares Outstanding 856,059,061